Laboratory Tests. 43 
TESTING BY THE CYANIDE PROCESS. 
Crush the well selected sample and pass it through 
at least a forty mesh sieve. Weigh out 500 grammes 
of the ore, shake with water, and insert a blue strip of 
litmus paper; if the litmus paper turns red an acid is 
present which must be removed. Neutralize the acid 
with lime by adding a little at a time and continue 
until the red litmus turns blue. Note the weight of 
lime required to neutralize the 500 grammes of ore. 
Wash the ore thoroughly with water, dry and weigh out 
four samples, each 100 grammes, and pour these into _ 
wide-necked unstoppered flasks which label No. 1, 2, 3, 
4, respectively. Measure out and pour into each flask 
or bottle, with the samples, 100cc of water (100 gms.). 
Now weigh out two lots of the cy salt, each 0.4 
grammes. Dissolve one lot with sample No. 1, the other 
lot with sample No. 2. Now 0.4 gms. : 100 gms. :: 8 
lbs. *: 2,000 lbs.; that is for each ton of water used in 
the milling process eight pounds of cyanide will be re- 
quired, or, since in practice one ton of ore is leached in 
one-half ton of water, one ton of ore would therefore be 
treated with four pounds of cyanide. Let No. 1 leach 
for, say twelve hours, and No. 2 for twenty-four hours, 
then filter off one assay ton (29.1%cc) of each solution 
_ and evaporate to dryness in a lead foil dish, made out of 
pure lead for the purpose, and when evaporation is com- 
pleted fold up lead dish and cupel; treating the result- 
ing button as in the regular assay of gold and silver 
ores. The difference between this assay and that of the 
ore before treating equals the amount of loss in treat- 
ing. Nos. 3 and 4 are tested in like manner, but for 
greater lengths of time, and with weaker solutions. The 
loss of liquid in the bottles due to evaporation should be 
estimated and allowed for in the assay. As a check on 
